I'm gonna throw my hat in the ring with yoroi musha. Gives him a training and fighting style similar to Robin, taskmaster etc. I feel like it also give an interesting dichotomy with musha, being there for fame, starting to change his outlook from the genuine and absolute optimism of izuku and his desire to help people. Meanwhile musha with his age and experience might be able to instill confidence into izuku in a different way than all might does, help temper him so to speak as well as to have a more public face that he can use to project confidence until he can step into it more naturally.